figure 1. ads-949 functional block diagram features ? 14-bit resolution ? 12.8mhz minimum sampling rate ? no missing codes over full military temperature range ? ideal for both time and frequency-domain applications ? excellent thd (C81db) and snr (78db) ? edge-triggered ? small, 32-pin, side-brazed, ceramic tdip or smt ? low-power, 2 watts ? low cost general description the low-cost ads-949 is a 14-bit, 12.8mhz sampling a/d converter. this device accurately samples full-scale input signals up to nyquist frequencies with no missing codes. excellent differential nonlinearity error (dnl), signal-to-noise ratio (snr), and total harmonic distortion (thd) make the ads-949 the ideal choice for both time-domain (ccd/fpa imaging, scanners, process control) and frequency-domain (radar, telecommunications, spectrum analysis) applications. the functionally complete ads-949 contains a fast-settling sample/hold ampli? er, a subranging a/d converter, an internal reference, timing/control logic, and error-correction circuitry. digital input and output levels are ttl. the ads-949 only requires the rising edge of a start convert pulse to operate. requiring only +15v, +5v and C5v supplies, the ads-949 typically dissipates just 2 watts. the device is offered with a bipolar input range of 2.5v and unipolar range of 0 to 5 volts. models are available for use in either commercial (0 to +70c) or military (C55 to +125c) operating temperature ranges. a proprietary, auto-calibrating, error-correcting circuit allows the device to achieve speci? ed performance over the full military temperature range. input/output connections pin function pin function 1 vin a 32 range 2 vin b 31 gain adjust 3 C5v 30 +5v analog 4 offset adj. 29 analog gnd 5 range ref. 28 +15v 6 2.5v ref. 27 +5v digital 7 start convert 26 digital gnd 8 eoc 25 overflow 9 enable 24 msb 10 bit 14 (lsb) 23 bit 1 (msb) 11 bit 13 22 bit 2 12 bit 12 21 bit 3 13 bit 11 20 bit 4 14 bit 10 19 bit 5 15 bit 9 18 bit 6 16 bit 8 17 bit 7 ref dac register register output register 10 bit 14 (lsb) 11 bit 13 12 bit 12 13 bit 11 14 bit 10 15 bit 9 16 bit 8 17 bit 7 18 bit 6 19 bit 5 20 bit 4 21 bit 3 22 bit 2 23 bit 1 (msb) 24 msb timing and control logic offset adjust 4 vin a 1 start convert 7 eoc 8 gain adjust 31 +5v analog suppl 30 +5v digital suppl 27 v range 32 C5.2v suppl 3 +15v suppl 28 analog ground 29 digital ground 26 C + s/h buffer digital correction logic flash adc 1 flash adc 2 power and grounding amp 9 enable 25 overflow vin b 2 2.5 v ref 6 ads 949 14 bit, 12.8mhz sampling a/d converters ?? datel ? 11 cabot boulevard, mans? eld, ma 02048-1151 usa ? tel: (508) 339-3000 ? www.datel.com ? e-mail: help@datel.com 01 apr 2011 mda_ads-949.b03 page 1 of 8
+25c 0 to +70c C55 to +125c analog input min. typ. max. min. typ. max. min. typ. max. units bipolar input voltage range ? 1 2.5 1 2.5 1 2.5 volts unipolar input voltage range ? 0 to 2 0 to 5 0 to 2 0 to 5 0 to 2 0 to 5 volts input resistance (vin a) 400 400 400 input capacitance 6 15 6 15 6 15 pf digital input logic levels logic "1" +2.0 +2.0 +2.0 volts logic "0" +0.8 +0.8 +0.8 volts logic loading "1" +20 +20 +20 a logic loading "0" C20 C20 C20 a start convert positive pulse width ? 50 50 50 ns static performance resolution 14 14 14 bits integral nonlinearity 0.75 0.75 1 lsb differential nonlinearity (f in = 10khz) C0.95 0.5 +1.25 C0.95 0.5 +1.25 C0.95 0.5 +1.5 lsb full scale absolute accuracy 0.15 0.4 0.15 0.4 0.4 0.8 %fsr bipolar zero error (tech note 2) 0.1 0.3 0.1 0.3 0.3 0.6 %fsr gain error (tech note 2) 0.2 0.4 0.2 0.4 0.4 1.5 % no missing codes (f in = 10khz) 14 14 14 bits dynamic performance peak harmonics (C0.5db) dc to 1mhz C83 C76 C83 C75 C79 C71 db 1mhz to 2.5mhz C78 C72 C78 C72 C73 C68 db 2.5mhz to 5mhz C76 C71 C76 C71 C71 C65 db total harmonic distortion (C0.5db) dc to 1mhz C81 C74 C81 C74 C77 C70 db 1mhz to 2.5mhz C76 C71 C76 C71 C72 C66 db 2.5mhz to 5mhz C74 C69 C74 C69 C69 C63 db signal-to-noise ratio (w/o distortion, C0.5db) dc to 1mhz 72 78 72 78 70 78 db 1mhz to 2.5mhz 72 77 72 77 70 77 db 2.5mhz to 5mhz 72 76 72 76 70 76 db signal-to-noise ratio ? (& distortion, C0.5db) dc to 1mhz 70 77 70 74 68 73 db 1mhz to 2.5mhz 70 74 70 74 66 71 db 2.5mhz to 5mhz 69 73 69 73 65 70 db noise 150 150 150 vrms two-tone intermodulation distortion (f in = 2.45mhz, 1.975mhz, f s = 10mhz, C0.5db) C82 C82 C82 db input bandwidth (C3db) small signal (C20db input) 30 30 30 mhz large signal (C0.5db input) 20 20 20 mhz feedthrough rejection (f in = 5mhz) 85 85 85 db slew rate 400 400 400 v/s aperture delay time +5 +5 +5 ns aperture uncertainty 2 2 2 ps rms functional specifications (t a = +25c, +v dd = +5v, Cv dd = C5v, +vcc = +15v, 12.8mhz sampling rate, 2.5v input range, and a minimum 3 minute warmup ? unless otherwise speci? ed.) absolute maximum ratings parameters limits units +5v supply (pins 27, 30) 0 to +6 volts +15v supply (pin 28) 0 to +16 volts C5v supply (pin 3) 0 to C5.5v volts digital input (pin 7) C0.3 to +v dd +0.3 volts analog input (pins 1, 2) 5 volts lead temperature (10 seconds) +300 c parameters min. typ. max. units operating temp. range, case ads-949mc, gc 0 +70 c ads-949mm, gm, C55 +125 c thermal impedance jc 6 c/watt ca 23 c/watt storage temperature range C65 +150 c package type 32-pin, side-brazed, ceramic tdip or smt weight 0.46 ounces (13 grams) physical/environmental ads 949 14 bit, 12.8mhz sampling a/d converters ?? datel ? 11 cabot boulevard, mans? eld, ma 02048-1151 usa ? tel: (508) 339-3000 ? www.datel.com ? e-mail: help@datel.com 01 apr 2011 mda_ads-949.b03 page 2 of 8
+25c 0 to +70c C55 to +125c dynamic performance (cont.) min. typ. max. min. typ. max. min. typ. max. units s/h acquisition time ( to 0.003%fsr, 5v step) 40 45 40 45 40 45 ns overvoltage recovery time 100 100 100 ns a/d conversion rate 12.8 12.8 12.8 mhz digital outputs logic levels logic "1" +2.4 +2.4 +2.4 volts logic "0" +0.4 +0.4 +0.4 volts logic loading "1" C4 C4 C4 ma logic loading "0" +4 +4 +4 ma output coding digital outputs power supply ranges +5v supply +4.75 +5.0 +5.25 +4.75 +5.0 +5.25 +4.9 +5.0 +5.25 volts C5.2v supply C4.75 C5.2 C5.45 C4.75 C5.2 C5.45 C4.9 C5.2 C5.45 volts +15v supply +14.5 +15 +15.5 +14.5 +15 +15.5 +14.5 +15 +15.5 volts power supply currents +5v supply +250 +260 +250 +260 +250 +260 ma C5.2v supply C200 C210 C200 C210 C200 C210 ma +15v supply +14.5 +15 +15.5 +14.5 +15 +15.5 +14.5 +15 +15.5 volts power dissipation 2.0 2.25 2.0 2.25 2.0 2.25 watts power supply rejection 0.1 0.1 0.1 %fsr/%v footnotes: technical notes 1. obtaining fully speci? ed performance from the ads-949 requires careful attention to pc card layout and power supply decoupling. the devices analog and digital ground systems are connected to each other internally. for optimal performance, tie all ground pins (26 and 29) directly to a large analog ground plane beneath the package. bypass all power supplies to ground with 4.7f tantalum capacitors in parallel with 0.1f ceramic capacitors. locate the bypass capacitors as close to the unit as possible. 2. the ads-949 achieves its speci? ed accuracies without the need for external calibration. it is recommended that the +5va and +5vd supplies should be powered up from the same source. if required, the devices small initial offset and gain errors can be reduced to zero using the adjustment circuitry shown in figure 2, 3. when using this circuitry, or any similar offset and gain calibration hardware, make adjustments following warmup. to avoid interaction, always adjust offset before gain. 3. applying a start convert pulse while a conversion is in progress (eoc = logic 1) will initiate a new and inac- curate conversion cycle. data for the interrupted and subsequent conversions will be invalid. 4. a passive bandpass ? lter is used at the input of the a/d for all production testing. ? all power supplies should be on before applying a start convert pulse. all supplies and the clock (start convert pulses) must be present during warmup periods. the device must be continuously converting during this time. ? contact datel for other input voltage ranges. ? a 50ns wide start convert pulse is used for all production testing. for applications requiring less than an 12.8mhz sampling rate, wider start convert pulses can be used. the rising edge of the start convert pulse needs to be as sharp as possible (<10 ns). otherwise, a degradation in performance can result from a slow rising edge pulse. ? effective bits is equal to: (snr + distortion) C 1.76 + 20 log full scale amplitude actual input amplitude 6.02 straight binary, offset binary ads 949 14 bit, 12.8mhz sampling a/d converters ?? datel ? 11 cabot boulevard, mans? eld, ma 02048-1151 usa ? tel: (508) 339-3000 ? www.datel.com ? e-mail: help@datel.com 01 apr 2011 mda_ads-949.b03 page 3 of 8
calibration procedure any offset and/or gain calibration procedures should not be implemented until devices are fully warmed up. to avoid interaction, offset must be adjusted before gain. the ranges of adjustment for the circuits in figures 2 and 3 are guaranteed to compensate for the ads-949s initial accuracy errors and may not be able to compensate for additional system errors. a/d converters are calibrated by positioning their digital outputs exactly on the transition point between two adjacent digital output codes. this can be accomplished by connecting leds to the digital outputs and adjusting until certain leds ? icker equally between on and off. other approaches employ digital comparators or microcontrollers to detect when the outputs change from one code to the next. offset adjusting for the ads-949 is normally accomplished at the point where the msb is a 1 and all other output bits are 0s and the lsb just changes from a 0 to a 1. this digital output transition ideally occurs when the applied analog input is +? lsb (+153v). gain adjusting is accomplished when all bits are 1s and the lsb just changes from a 1 to a 0. this transition ideally occurs when the analog input is at +full scale minus 1? lsb's (+2.49954v). zero/offset adjust procedure 1. apply a train of pulses to the start convert input (pin 7) so the converter is continuously converting. 2. apply +153v to the analog input (pin 1). 3. adjust the offset potentiometer until the output bits are 10 0000 0000 0000 and the lsb ? ickers between 0 and 1. gain adjust procedure 1. apply +2.49954v to the analog input (pin 1). 2. adjust the gain potentiometer until all output bits are 1s and the lsb ? ickers between 1 and 0. 3. to con? rm proper operation of the device, vary the input signal to obtain the output coding listed in table 2. input voltage zero adjust gain adjust range +? lsb +fs C1? lsb 2.5v +153v +2.49954v table 1. gain and zero adjust figure 2. typical ads-949 bipolar connection diagram 0.1f 4.7f 27 +5vd 29 agnd 3 C5v ads-949 20k 4.7f +5va 26 dgnd C5v +5v 1vin a 4 offset adjust 7 start convert 23 22 21 20 19 18 17 16 15 14 13 12 11 10 8 bit 1 (msb) bit 2 bit 3 bit 4 bit 5 bit 6 bit 7 bit 8 bit 9 bit 10 bit 11 bit 12 bit 13 bit 14 (lsb) eoc bipolar analog input start convert ? bypass pins 5, 6, 32, with a 4.7f to analog ground. note the voltage value at pin 32 (range) sets the input voltage range of the ads-949 eg if pin 6 (2.5v reference out) is tied to the range pin 32 (20k pot is shorted), then the input range of the ads-949 becomes 2.5v if the 20k pot is set at midrange then the input range of the ads-949 becomes 1.25v + ero/ offset adjust C5v +5v 31 gain adjust gain a djust 20 C5v 2 vin b 9 enable 20k 6 2.5v ref ? 32 range ? +15v 28 +15v +5vd 4.7f + 30 +5va 0.1f 0.1f 4.7f + 0.1f + 5 range ref ? ads 949 14 bit, 12.8mhz sampling a/d converters ?? datel ? 11 cabot boulevard, mans? eld, ma 02048-1151 usa ? tel: (508) 339-3000 ? www.datel.com ? e-mail: help@datel.com 01 apr 2011 mda_ads-949.b03 page 4 of 8
electrically-insulating, thermally-conductive "pads" may be installed underneath the package. devices should be soldered to boards rather than socketed, and of course, minimal air ? ow over the surface can greatly help reduce the package temperature. in more severe ambient conditions, the package/junction temperature of a given device can be reduced dramatically (typically 35%) by using one of datel's hs series heat sinks. see ordering information for the assigned part number. see page 1-183 of the datel data acquisition components catalog for more information on the hs series. request datel application note an8, "heat sinks for dip data converters", or contact datel directly, for additional information. thermal requirements all datel sampling a/d converters are fully characterized and speci? ed over operating temperature (case) ranges of 0 to +70c and C55 to +125c. all room temperature (t a = +25c) production testing is performed without the use of heat sinks or forced air cooling. thermal impedance ? gures for each device are listed in their respective speci? cation tables. these devices do not normally require heat sinks, however, standard precautionary design and layout procedures should be used to ensure devices do not overheat. the ground and power planes beneath the package, as well as all pcb signal runs to and from the device, should be as heavy as possible to help conduct heat away from the package. figure 3. typical ads-949 unipolar connection diagram table 3. output coding unipolar input volt. output coding input volt. bipolar scale 0 to +5v msb lsb msb lsb 2.5v scale +fs C 1 lsb +4.999695 11 1111 1111 1111 01 1111 1111 1111 +2.499695 +fs C 1lsb +7/8 fs +4.375000 11 1000 0000 0000 01 1000 0000 0000 +1.875000 +3/4fs +3/4 fs +3.75000 11 0000 0000 0000 01 0000 0000 0000 +1.250000 +1/2fs +1/2 fs +2.500000 10 0000 0000 0000 00 0000 0000 0000 0.000000 0 +1/4 fs +1.250000 01 0000 0000 0000 11 0000 0000 0000 C1.250000 C1/2fs +1/8 fs +0.625000 00 1000 0000 0000 10 1000 0000 0000 C1.875000 C3/4fs +1 lsb +0.000305 00 0000 0000 0001 10 0000 0000 0001 C2.499695 Cfs+1lsb 0 0.000000 00 0000 0000 0000 10 0000 0000 0000 C2.500000 Cfs straight bin. off. binary two's comp. 0.1f 4.7f 27 +5vd 29 agnd 3 C5v ads-949 20k 4.7f +5va 26 dgnd C5v +5v 1vin a 4 offset adjust 7 start convert 23 22 21 20 19 18 17 16 15 14 13 12 11 10 8 bit 1 (msb) bit 2 bit 3 bit 4 bit 5 bit 6 bit 7 bit 8 bit 9 bit 10 bit 11 bit 12 bit 13 bit 14 (lsb) eoc unipolar analog input start convert + ero/ offset adjust C5v +5v 31 gain adjust gain a djust 20 C5v 2 vin b 9 enable 20k 6 2.5v ref ? 32 range ? +15v 28 +15v +5vd 4.7f + 30 +5va 0.1f 0.1f 4.7f + 0.1f + 5 range ref ? ads 949 14 bit, 12.8mhz sampling a/d converters ?? datel ? 11 cabot boulevard, mans? eld, ma 02048-1151 usa ? tel: (508) 339-3000 ? www.datel.com ? e-mail: help@datel.com 01 apr 2011 mda_ads-949.b03 page 5 of 8
figure 4. fft analysis of ads-949 (fs = 12.8mhz, ? n = 3.85mhz, vin = C0.5db, 16,384 point fft) figure 5. ads-949 histogram figure 6. ads-949 timing diagram start convert minimum is 40ns output data enabled eoc n notes: 1. scale is approximately 10ns per division. all values are typical. 2. rising edge of the start convert needs to be less than 10 ns. data out enabled n+1 40ns 40ns 20ns 60ns data n-3 data n-2 data n-1 data n 30ns 20ns data n-3 data n-2 data n-1 data n hz hz hz hz ads 949 14 bit, 12.8mhz sampling a/d converters ?? datel ? 11 cabot boulevard, mans? eld, ma 02048-1151 usa ? tel: (508) 339-3000 ? www.datel.com ? e-mail: help@datel.com 01 apr 2011 mda_ads-949.b03 page 6 of 8
figure 7. ads-949 evaluation board schematic (ads-b949) contact datel for schematic ads 949 14 bit, 12.8mhz sampling a/d converters ?? datel ? 11 cabot boulevard, mans? eld, ma 02048-1151 usa ? tel: (508) 339-3000 ? www.datel.com ? e-mail: help@datel.com 01 apr 2011 mda_ads-949.b03 page 7 of 8
receptacles for pc board mounting can be ordered through amp, inc., part # 3-331272-8 (component lead socket), 32 required. for mil-std-883 product specifcation, contact datel. mechanical dimensions inches (mm) 1.62 ma . (41.15) 0.92 ma . (23.37) 0.018 t p. (0.46) 1.50 t p (38.10) 0.100 t p. (2.54) 0.05 t p. (1.27) 0.175 t p (4.45) 0.05 t p. (1.27) 0.220 t p. (6.86) 0.90 t p. (22.86) 0.010 t p. (0.254) dimension tolerances (unless otherwise indicated): 2 place decimal (. ) 0.010 (0.254) 3 place decimal (. ) 0.005 (0.127) lead material ovar alloy lead finish 50 microinches (minimum) gold plating over 100 microinches (nominal) nickel plating pin 1 inde 0.05 t p. ( 1.27 ) seating plane operating 32-pin model temp. range package ads-949mc 0 to +70c tdip ads-949mm C55 to +125c tdip ads-949/883 C55 to +125c tdip ads-949gc 0 to +70c smt ADS-949GM C55 to +125c smt ordering information accessories ads-b949 evaluation board (without ads-949) hs-32 heat sink for ads-949 tdip models ads 949 14 bit, 12.8mhz sampling a/d converters . makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. the descriptions contained her ein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. speci? cations are subject to change without notice. www.datel.com ? e-mail: help@datel.com ?? datel 11 cabot boulevard, mans? eld, ma 02048-1151 usa itar and iso 9001/14001 registered 01 apr 2011 mda_ads-949.b03 page 8 of 8
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